For many years the problem of disposability has plagued the industries which provide disposable diapers, incontinent garments and feminine care products. While much headway has been made in addressing this problem, one of the weak links has been the inability to create an economical coherent fibrous web which will readily dissolve or disintegrate in water. See, for example, U.K. patent disclosure 2,241,373 and U.S. Pat. No. 4,186,233. Without such a product, the ability of the user to dispose of the product by flushing it down the toilet is greatly reduced if not eliminated. Furthermore, the ability of the product to disintegrate in a landfill is quite limited because a large portion of the components of the product, which may well be biodegradable or photodegradable, are encapsulated in plastic which degrades over a long period of time, if at all. Accordingly, if the plastic at least disintegrated in the presence of water, the internal components could degrade as a result of the rupture of the plastic encapsulation.
In prior U.S. patent application Ser. No. 07/997,797 entitled "Hydrodisintegratable Material and Products Formed Thereby" which was filed on Dec. 29, 1992, a composition is described which has the ability to disintegrate in the presence of water. Thin material can be used to form plastic films which disintegrate in the presence of water. However, those in the art have also been searching for a fibrous material or web (as compared to a film) which has the ability to disintegrate in the presence of water.
Disposable diapers, feminine care products and adult incontinent care products generally usually have a body side liner which must rapidly pass fluids such as, for example, urine or menses, so that the fluid may be absorbed by the absorbent core of the product. Typically, the body side liner is a cohernet fibrous web which desirably possesses a number of characteristics such as softness and flexibility. The fibrous webs of the body side liner material are typically formed by wet or dry (air) laying a generally random plurality of fibers and joining them together to form a coherent web with a binder. Past binders have preformed this function well. From an environmental standpoint it might be stated that the past binders have performed this function too well in that the binders tended not to degrade and thus the .liner remained intact. This action severely hampered any environmental degradation of the disposable product.
Wet and dry (air) laid webs which disintegrate in the presence of water are generally known in the art. However, a problem with these webs is that they lack strength and cannot be effectively utilized in a consumer product because of their proclivity to rapidly fall apart. Thus, an impression of a "cheap" product can result in the mind of the consumer. Accordingly, a desirable attribute which those of skill in the art have been seeking was to discover a binder composition which increased the strength of wet and dry (air) laid webs but still allow the bonded coherent web to rapidly disintegrate to a group of generally individual fibers once it was placed in an aqueous environment. In attempting to design a porous, fibrous, web resort was first had to the teachings of the aforesaid '797 application. However, the use of that material as a binder resulted in a generally stiff material which did not appear to be desirable.